The concept of a project life cycle

What is the purpose of having

a project life cycle?

To define the activities to be carried out in a

systems development project.

To introduce consistency among many systems

development projects in the same organization.

To provide checkpoints for management control

for go/no-go decisions.

The classical project life

cycle

The survey phase and the analysis phase may be lumped

together into a single phase (this is especially common in

organizations in which anything the user wants is deemed

at the outset to be feasible).

There may not be a phase called hardware study if it can be

taken for granted that any new system can be implemented

on an existing computer without causing any major

operational impact.

The preliminary design and detail design phases may be

lumped together in a single phase simply called design.

Several of the testing phases may be grouped together into

a single phase; indeed, they may even be included with

coding.

Bottom-Up Implementation

Nothing is done until it's

all

done.

Module testing uncovers relatively simple

logic errors inside individual modules.

Debugging tends to be extremely difficult

during the final stages of system testing.

The requirement for computer test time

usually rises exponentially during the

final stages of testing.

Sequential Progression

sequential approach doesn't allow for real-

world phenomena having to do with

personnel

we rarely do a complex job right the first

time, but we are very good at making

repeated improvements to an imperfect job

the user may change his or her mind about

what the system should do

the classical project life cycle relies on

outdated techniques

The semi structured life

cycle

The bottom-up sequence of coding,

module testing, and system testing is

replaced by top-down implementation

Approach where high-level modules are

coded and tested first, followed by the

lower-level, detailed modules.

Strong indication that structured

programming is to be used as the method

of actually coding the system.

Classical design is replaced by structured

design.

The structured project life

cycle

The Survey

Systems Analysis

Design

Implementation

Acceptance Test Generation

Quality Assurance

Procedure Description

Database Conversion

Installation

Radical versus conservative

top-down implementation

In the most extreme

situation, all the

activities in the

structured project life

cycle could be taking

place simultaneously

in a

conservative

approach to the

structured project life

cycle, all of activity N

is completed before

activity N + 1 begins.

How does a project manager

decide whether to adopt a

radical or conservative

approach?

How fickle is the user?

What pressure is the project team under to

produce immediate, tangible results?

What pressure is the project manager under

to produce an accurate schedule, budget,

and estimate of people and other

resources?

What are the dangers of making a major

technical blunder?

The Prototyping life cycle

An alternative approach to

requirements definition is to capture

an initial set of needs and to

implement quickly those needs with

the stated intent of iteratively

expanding and refining them as

mutual user/developer understanding

of the system grows

Good candidates for a

prototyping approach

The user is unable (or unwilling) to examine

abstract paper models like dataflow diagrams.

The user is unable or unwilling to articulate (or

“prespecify”) his or her requirements in any

form and can only determine the requirements

through a process of trial and error.

The system is intended to be on-line with full-

screen terminal activities, as opposed to batch

edit, update, and report systems.

Document Outline